ECHINOCARDIUM CORDATUM. 349 



SPATANGINA. 



Subfamily Spatangina Gray, 1855. Cat. Rec. Ech. 



ECHINOCARDIUM. 



Echinocardium Gray, 1825. Ann. Phil. 



Test thin, heart-shaped. Ambulacral petals more or less triangular, inter- 

 rupted at apex by an internal fasciole ; pores of lateral pairs of ambulacra dis- 

 tant, broad anterior ambulacrum formed of small pores situated in a more or 

 less distinct groove. Anal system placed in the vertically truncated posterior 

 extremity. Subanal fasciole with ascending branches around anal system- 

 Spines of lower surface long, spatuliform, while those of the rest of the test 

 are thin and silk-like. I attempted formerly to distinguish Amphidetus and 

 Echinocardium on account of the more ovoicl shape of the test and the dis- 

 connected posterior fascioles of (Amphidetus) Echinocardium flavescens; the 

 little thus far known of the development of Echinocardium cordatum shows 

 satisfactorily that such characters are not generic. 



Echinocardium cordatum 



Echinus cordatus Fexn. 17 77. Brit. Zool. 



! Echinocardium conlalum Gray, 1848. Brit. Rad. 



PI XIX. f. 10 - 17 ; PL XX. f. 5-7. 



Test thin, heart-shaped from above, vertex posterior, test rising gradually 

 as a rounded keel beyond the internal fasciole, truncated at both extremities, 

 odd ambulacrum sunken more than the lateral ones, the test forming a ridge 

 on both sides of the anterior depression. The abactinal portion of the odd 

 sunken ambulacrum is bounded by the broad internal fasciole, this gradually 

 becomes narrower towards the anterior extremity. The pores of the odd am- 

 bulacrum are small, comma-shaped, so closely packed together on the flat por- 

 tion of the groove as to alternate, though arranged singly towards the abacti- 

 nal pole and towards the actinostome. Four ovarian openings diverging 

 posteriorly. The anterior rows of pores of the lateral ambulacra are obliter- 

 ated by the internal fasciole. The lateral ambulacral petals are triangular ; 

 adjoining rows of pores of the lateral ambulacra form crescents in the lateral 

 and posterior ambulacral spaces. The anal system is vertically elliptical. The 



